Smith opted to run as most every other top Republican in the state, including former Reps. Charlie Bass and Jeb Bradley, decided against it.

For months, Republicans have been waiting for word from former Sen. Scott P. Brown, R-Mass., who has spent a considerable amount of time in the Granite State this year and is considering a challenge to Shaheen. He is still undecided, but Republicans in the state, including Sen. Kelly Ayotte, have said he would put the seat in play.

If anyone knows about running for office in a new state, it's Smith. He briefly ran for Senate in Florida in 2004, two years after his primary defeat to then-Rep. John E. Sununu, but found little support — as he did when he tried again in 2010. Sununu went on to defeat then-Gov. Shaheen in the general election.

Smith had a conservative voting record in the Senate, but he briefly left the Republican Party in 1999 while running for president. He dropped out of the race after a few months and rejoined the party. He endorsed Sen. John Kerry in the 2004 presidential election.